(1) Field of the Invention
The present invention relates to the art of continuous molten metal casting. More specifically, it relates to the clamping of an inner nozzle in a continuous casting facility.
(2) Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
In a casting facility, the molten metal is generally contained in a metallurgical vessel, for example a tundish, before being transferred to another container, for example into a casting mould. The metal is transferred from the vessel to the container via a nozzle system provided in the base of the metallurgical vessel, comprising an inner nozzle located at least partly in the metallurgical vessel and coming into tight contact with a sliding transfer plate (or casting plate) located below and outside of the metallurgical vessel and brought into registry with the inner nozzle via a device for holding and replacing plates, mounted under the metallurgical vessel. This sliding plate may be a calibrated plate, a casting tube or a saggar comprising two or more plates. Since all these types of plates are part of a nozzle comprising a plate connected to a tubular section of varying lengths depending on the applications and to distinguish them from valve gates used, e.g., in a ladle, they will be referred to herein as “sliding nozzle”, “pouring nozzle”, “exchangeable pouring nozzle” or combinations thereof. The pouring nozzle can be used to transfer the molten metal in the form either of a free flow with a short tube, or of a guided flow with a longer, partly submerged casting tube.
An example of such casting facility is described in the document EP1289696. To provide tight contact between the inner nozzle and the sliding pouring nozzle, the device for holding and replacing tubes comprises clamping means, intended to press against the inner nozzle, particularly downwards, and pushing means, intended to press on the sliding plate of the pouring nozzle, particularly upwards, so as to press the inner nozzle and the pouring nozzle against each other. These clamping and pressing means are generally arranged along the longitudinal edges of the inner nozzle and the sliding plate, the longitudinal direction corresponding to the plate replacement direction.
One difficulty lies in the fact that the tightness of the inner nozzle/sliding plate interface must be as perfect as possible, lest the molten metal may flow is between the two parts, damaging the surfaces of the refractory elements when replacing the pouring nozzle with a new one. Furthermore, the lack of tightness (contact between the two refractory elements) enables air to infiltrate, which is harmful both for the refractory elements and for the cast metal quality.
The present invention aims at enhancing the tightness of the contact surfaces between the inner nozzle plate and the sliding plate of the pouring nozzle. The present invention also aims at optimising the stress distribution in the refractory elements, for increasing their service time.